A. Construction of pBBE22-ospA', pBBE22-ospE', and pBBE22-vlsE'. The flaB promoter region (flaBp) and a promoterless ospA, ospE, or vlsE gene were PCR amplified, fused, and cloned into pBBE22.
B. Generation of OspC-deficient B. burgdorferi with increased OspC, OspA, OspE, DbpA or VlsE expression. pBBE22-ospA', pBBE22-ospA', pBBE22-ospE', pBBE22-dbpA', pBBE22-vlsE', and pBBE22 were electroporated into the ospC mutant. pBBE22-ospC' and pBBE22-dbpA' were constructed in our previous studies (Xu et al., 2006; Xu et al., 2007b). The parental clone 13A, the ospC mutant, and transformants ΔospC/ospC'/1, ΔospC/ospC'/2, ΔospC/ospA'/1, ΔospC/ospA'/2, ΔospC/ospE'/1, ΔospC/ospE'/2, ΔospC/vlsE'/1, and ΔospC/vlsE'/2 were verified for Osp expression by immunoblots probed with FlaB, OspC and OspA MAbs, and mouse antisera raised against recombinant OspE, DbpA and VlsE.